The present invention relates to an air supply and exhaust adapter that is attached to an air supply aperture and to an exhaust aperture of a combustion device.
Conventionally, hot water supply devices and room heating devices have been widely used that perform hot water supply and/or space heating by employing natural exhaust type (CF: Conventional Flue type) combustion devices that are installed inside a building, and that combust fuel by taking in air from within the building and discharge the combustion exhaust gases to the exterior of the building by the force of natural venting. An exhaust pipe that communicates with the exterior is provided to the building, and, since the exhaust unit of the CF type combustion device is connected to the exhaust pipe, accordingly the combustion exhaust gases can be discharged to the exterior.
When a combustion device of this CF type is to be replaced with a new one, sometimes, from the viewpoint of maintaining the external appearance of the building, there are cases that it is not possible to remove an exhaust pipe that is already in existence. In such a case, one solution is to replace the combustion device by inserting a new exhaust pipe into the interior of the exhaust pipe that is already in existence.
For example, the exhaust construction for a combustion device of Japanese Patent Publication 5,884,865 is connected to an exhaust unit of a forced exhaust type (FE: Forced Exhaust type) combustion device that combusts fuel by forcibly sucking in air from the inside of the building with a blower fan, and that vents the resulting combustion exhaust gases to the outside. This exhaust construction makes it possible to discharge combustion exhaust gases to the outside by passing an exhaust conduit through the interior of an exhaust pipe that is already in existence, and also prevents the intrusion of rain water by disposing an air supply and exhaust adapter in the space between the exhaust pipe and the exhaust conduit. Moreover, this space is connected to a connection port that is provided on the outer casing of the combustion device, and, by utilizing the negative gauge pressure within the outer casing that is generated during operation of the blower fan, it becomes possible to send combustion exhaust gases that have leaked out into the space between the exhaust pipe and the exhaust conduit back into the combustion device for a second time.
However, when it is not possible to remove the already existing exhaust pipe, it is often not possible to provide a new air supply pipe. For this reason, it may not be possible to replace a CF type combustion device or an FE type combustion device with a forced air supply and exhaust type (FF: forced flue or forced draft balanced flue type) combustion device that sucks in outdoor air from an air supply pipe with a blower fan, combusts fuel, and discharges the exhaust to the exterior, which in recent years has become a mainstream type. Accordingly, it is necessary to provide a FE type combustion device as a replacement, and this constitutes a burden upon the supplier of combustion equipment.
Even if an FF type combustion device is installed by passing a new exhaust conduit through an exhaust pipe that is already in existence, so that air inside the building is sucked in and the exhaust gases are discharged to the exterior of the building, there is a danger that the exhaust gases may leak from the exhaust conduit to the interior of the building. Since, with the exhaust construction for a combustion device described in above patent publication, the space between the exhaust pipe and the exhaust conduit is connected to a connection port on the outer casing of an FE type combustion device in order to prevent leakage of the combustion exhaust gases into the building, accordingly, normally, this exhaust construction cannot be applied to an FF type combustion device that is not provided with any connection port of this type on its outer casing for introduction of outdoor air.
An object of the present invention is to provide an air supply and exhaust adapter which makes it possible to employ an FF type combustion device in a safe manner by utilizing an exhaust pipe that is already in existence, even in a site in which it is not possible to install an air supply pipe.